Minimal green space by the way (5)
I believe the answer is:
least
'minimal' is the definition.
(similar in meaning)
'green space by the way' is the wordplay.
'green space' becomes 'lea' (type of field).
'by' is a charade indicator (letters next to each other).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'way' becomes 's' (Compass direction - South).
't' after 's' is 'st'.
'lea'+'st'='LEAST'
(Other definitions for least that I've seen before include "Smallest, being stale" , "No more petty" , "Most insignificant" , "To the lowest degree" , "Bottom" .)